The invention relates to desensitizing teeth.
The dentin layer in a tooth generally contains channels, or tubules, extending from the pulpal surface to the peripheral surface located interior to the enamel and cementum. Exposure of these tubules in the dentin may occur through the loss of enamel and/or gingival recession accompanied by a loss of cementum. It has been theorized that these exposed tubules are in part responsible for the hypersensitivity to external stimuli, such as hot or cold fluids, or applied mechanical pressures often exhibited by teeth.
The problem of hypersensitive teeth is well-recognized, and various treatments have been proposed in the art. Pashley et al., U.S. Pat. No. 4,057,021, describes desensitizing hypersensitive teeth by applying an aqueous solution of alkali metal salts and ammonium oxalate to the surface of the teeth. Kim, U.S. Pat. Nos. 4,631,185 and 4,751,072, describes desensitizing teeth by treatment with potassium salts. Neirinckx, U.S. 4,990,327, describes desensitizing teeth with strontium ion and fluoride ion. Mason, U.S. Pat. No. 4,992,258, describes desensitizing teeth by applying a dentifrice including a montmorillonite clay. Lutz, U.S. Pat. No. 4,011,309, describes a desensitizing dentifrice composition that includes citric acid, sodium citrate, and non-ionic polyol surfactant. Mlkvy et al., U.S. Pat. Nos. 3,888,976 and 3,772,431 describe using a zinc or strontium ion containing astringent-desensitizing agent in an effervescent mouthwash tablet. Hodosh, U.S. Pat. No. 3,863,006, describes desensitizing teeth with a nitrate salt. Svajda, U.S. Pat. No. 3,689,636, describes desensitizing teeth with solutions of chloride salts. Rosenthal, U.S. Pat. No. 3,122,483, describes desensitizing teeth with strontium ions. Scheller, U.S. Pat. Nos. 4,634,589 and 4,710,372, describe a dentifrice containing apatite particles for treating hypersensitive teeth.
It is known that dentifrices may include particles which thicken or color the dentifrice, or which make the dentifrice abrasive. For example, in Scheller '589 and '372, the apatite particles are included in the dentifrice to roughen the surface of the teeth. See also, Thuersson et al., U.S. Pat. No. 3,226,297 (e.g., col. 4, lines 34-43); Blunt, U.S. Pat. No. 3,475,369 (e.g., col. 12, lines 27-34); Patino et al., U.S. Pat. No. 4,007,259 (e.g. col. 1, line 30); Bossard, U.S. Pat. No. 2,994,642 (e.g., col. 4, lines 40-60); La Follette, U.S. Pat. No. 3,357,950 (e.g., col 1, lines 50-61); Adams, U.S. Pat. No. 3,357,951 (e.g. col. 1, lines 49-61); Muhler, U.S. Pat. No. 3,450,813; Watson, U.S. Pat. No. 3,934,001; Naumann et al., U.S. Pat. No. 3,978,206 (e.g., col. 1, lines 39-57); Davis, U.S. Pat. No., 4,102,992; and Humphries et al., U.S. Pat. No. 4,963,347.
Jernberg, U.S. Pat. No. 4,685,883, describes using biodegradable microspheres to deliver chemotherapeutic agents to lesions in the gums.
Dichter et al., U.S. Pat. No. 3,956,480 describes treating teeth with anionic polymers complexed with a cationic germicide, such as chlorhexidine.